Prediction of surface generation in microgrinding of ceramic materials by coupled trajectory and finite element analysis

Objectives: The aim of this study was to analyze mechanical and thermal stresses of hybrid ceramic and lithium disilicate based ceramic of CAD/CAM inlays using 3D Finite element analysis. Material and Methods: A three dimensions finite element model of permanent maxillary premolar designed according to standard anatomy with class II cavity preparation for inlay restored with two different ceramic materials:- 1- Hybrid ceramic (Vita Enamic), 2- Lithium disilicate based ceramic (IPS e.max CAD). Totally six runs were performed on the model as: One loading case for each restorative material was tested in stress analysis; seven points of loading with 140N vertically applied at palatal cusp tip and cusp slop, marginal ridges and central fossa while the models base was fixed as a boundary condition in the two cases. Two thermal analysis cases were performed for each restoration material by applying 5ºC and 55ºC on the crown surface including the restoration surface. Results: The results of all structures were separated from the rest of the model to analyze the magnitude of stress in each component. For each group, maximum stresses on restorative materials, cement, enamel, and dentin were evaluated separately. Both ceramic materials generated similar stress distribution patterns for all groups when a total occlusal load of 140 N was applied. Conclusion: Thermal fluctuations of temperature have a great influence on the stresses induced on both restoration and tooth structure. IPS e.max CAD produced more favorable stresses on the tooth structure than Vita Enamic. KEYWORDS Ceramics; Finite element analysis; IPS e.max CAD; Lithium disilicate; Vita Enamic.

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Finite Element Analysis on Proof Testing of Ceramic Ball Heads for Total Hip Replacements: Trauma Loading Considerations

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.317-318.773 ◽

2006 ◽

Vol 317-318 ◽

pp. 773-776

Author(s):

Daniel G. Carillo ◽

M.C. Curiel ◽

Ho Sung Aum ◽

Soo Wohn Lee

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Contact Pressure ◽

Impact Load ◽

Ceramic Materials ◽

Test Scenario ◽

Element Analysis ◽

Hip Prostheses ◽

Hip Replacements ◽

As Stress

Trauma related loading of hip prostheses has been reported as a cause of failure of implanted ceramic materials, ball and/or cup. In this study a computer simulated model is made to evaluate contact pressures and stresses in the stem/ball contact pair, as well as stress concentration regions in the ceramic cup. A 3D Non-Linear Finite Element Analysis was performed in a “proof test” scenario. A high peak trauma-like loading of 15 KN was used. 28mm ball heads (in diameter) were modeled and two sizes for taper lock were simulated to report their influence on the contact pressure over the critical areas of the ballhead. It was found that the ball head cone’s depth has a major incidence in the stress and contact pressure surrounding the stem when an impact load is applied. The best stress and pressure configurations were found for the case of the stem lying completely inside the ballhead.

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